@shartne That’s a good question. The watt meter was reading the watts from
the panels but I did not specifically measure the watts to the battery at
the same moment. In reviewing the volts and amps to the battery it appears
that the losses were about 6.5%. For instance, at one point I showed 461w
from the panels and 431w to the battery (VxA using the Trimetric).

@Fearlessthinker Well that would be a more efficient use than the gti. But
then there would be the loss converting to ac to actually use the power
unless you have a dc refrigerator or lights which would be the best way to
get the most efficiency from your batteries.

@shartne Yes, good point. Batteries also lose their charge naturally over
time. There is no free lunch. My efforts are to help all of us understand
these trade-offs and maybe it will lead to some new innovations. Thanks
Scott … you’re videos a great inspiration to me and to the DIY crowd, so
keep them coming.

thanks for sharing your videos, I’m learning a lot from them. I am building
a small circuit and need to know if the wattmeter must be installed between
the panel and solar controller or between the solar controller and battery?

@rmfungaro It can be used in either place. Some people put one in both
places. I have mine between the panel and the solar controller becauase I
have meters already from the solar controller to the battery bank. Thanks.

Thanks so much for sharing your knowledge through your videos. I’ve picked
up some good information from you. But I di have a question I hope you
could answer for me. What is the maximum voltage you would charge a 12V
deep cycle battery bank with? I’m building a few large panels, and they are
either going to be 22V or 14V due to the size of the free glass I have. I’m
thinking 14V is not enough, and 22V is a little too high. Suggestions?
Thanks in advance, Doug

The voltage will be set by the battery, not the panels, however the panels
have to be capable in normal sun to produce a higher voltage than the
battery or no current will flow. If your 22V is the open circuit voltage,
then the maximum power point voltage will be about 17V which is good for
charging 12V battery banks.

Let’s talk about (1) 12V deep cycle battery rated at 110 AH capacity (C).
The rule of thumb is to charge at a max C/8 of the AH rating, so 13.75 amps
in “bulk” stage, then maintain a much lower rate for absorption and float
stages. Usiing a 3-stage charger like the Solar Boost takes care of these
stages. This is per 12V battery, btw.